The present invention is designed to minimize radial run out experienced by the attachment of an inboard disc rotor to a wheel hub for such applications as heavy truck wheel ends. Radial run out is a concern when attaching a brake rotor to a wheel hub to prevent vibration caused by disc rotor imbalance. The brake rotor must be concentrically aligned with the wheel hub prior to securing the disc rotor to the hub. Fasteners attach the disc rotor to the hub by extending through holes formed in a disc rotor mounting flange of the hub and threadably engaging a hub mounting flange on the disc rotor. Vibration may occur due to the disc rotor having an incorrect concentric alignment with the axis of the hub.
The method used to pilot and/or center an inboard mounted disc rotor to a wheel hub requires a machined pilot diameter of annular shape on the disc rotor that interfaces with a machined pilot diameter of annular shape on the wheel hub. Prior art pilot features are disposed between the axis of the hub and the wheel studs or generally, at a smaller pitch circle diameter than the pitch circles for either the disc rotor mounting fasteners and the wheel studs of the hub. This placement of the pilot feature formed a discontinuous section thickness of the hub body and flange by continuous or individual mounting bosses, machined undercut or small radius features form on the inboard flange region of the wheel hub. These notches and stress risers in the hub flange reduced the fatigue life of the hub.
Wheel hubs undergo cyclical and mean stresses that may be concentrated at an inboard flange area of the wheel hub. The stresses are particularly concentrated at discontinuous section thicknesses of the hub especially when such stress risers are formed at a pitch circle diameter equal to or less than the pitch circle diameter of the fasteners on the hub connecting the disc rotor or wheels. The stress risers formed by the prior art pilot features have a compounding effect to the cyclical and mean stresses of the wheel hub increasing the stress level at those points and reducing the fatigue life of the wheel hub.
It is desirable to provide a design and method of piloting the disc rotor on the wheel hub by positioning pilot features outside the pitch circle diameters of either the fasteners or studs. A benefit of such a design is to reduce the effects of fatigue on the wheel hub. It is further desirable to provide a method of piloting the disc rotor on the wheel hub where in the pilot features do not create stress risers.